|KELLER, SUSANNE - Us Food & Drug Administration (FDA)|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2018
Publication Date: 3/26/2019
Citation: Gurtler, J., Keller, S.E., Fan, X., Olanya, O.M., Jin, Z.T., Camp, M.J. 2019. Survival of Salmonella during apple dehydration as affected by apple cultivar and antimicrobial pretreatment. Journal of Food Protection. 82(4):628-644.
Interpretive Summary: Dried fruits, including apples and coconut, have been recalled for contamination with Salmonella. A study was conducted to determine if Salmonella inactivation, which takes place during the dehydration process, varies based on apple variety or antimicrobial rinse solution applied to apples before dehydration. Out of 6 apple varieties tested the greatest inactivation of Salmonella occurred on Granny Smith apples, which also had the lowest pH. Of 8 antimicrobial rinse solutions tested sodium acid sulfate (sodium bisulfate) completely eliminated Salmonella on apple slices following dehydration. These results should assist the dehydrated fruit industry in reducing Salmonella contamination associated with dried fruit.
Technical Abstract: Salmonella is capable of surviving dehydration processes of various foods including dried fruit. Dehydrated fruit, including dried coconut (Cocos nucifera) and dried apple (Malus sp.) slices, have been the subject of recalls due to contamination with Salmonella. A study was conducted to determine the survival of Salmonella on six cultivars of apple slices after dehydration as well as survival following a treatment with an antimicrobial solution (0.5 percent, wt./wt.) and dehydration. Six cultivars of apples (Envy, Gala, Red Delicious, Fuji, Pink Lady, Granny Smith) were cored and sliced into 0.4 mm rings, inoculated with a five-strain composite of desiccation-resistant Salmonella and dehydrated at 60 degrees Celsius for 5 hours. Subsequently, Gala apple slice were treated in 0.5 percent solutions of one of eight antimicrobial rinses for two minutes and then dehydrated at 60 degrees Celsius for 5 hours. Antimicrobial solutions were potassium sorbate (PS), sodium benzoate (SB), ascorbic acid (AA), propionic acid (PA), lactic acid (LA), citric acid (CA), fumaric acid (FA), and sodium acid sulfate (SAS). Reduction of Salmonella populations varied according to apple cultivar. Reductions (in log CFU) were Envy (1.69), Gala (2.09), Red Delicious (2.77), Fuji (2.93), Pink Lady (3.15), and Granny Smith (3.77). Greater numbers of Salmonella (p<0.05) were significantly inactivated on Granny Smith, Pink Lady and Fuji apples than on Gala and Envy apples. Survival of Salmonella on Gala apple slices (log CFU) following antimicrobial treatments and dehydration were untreated control (5.58), PS (4.76), SB (3.90), AA (3.29), PA (3.13), LA (2.89), CA (2.83), FA (1.76), and SAS (0.0). Lower survival was obtained by pre-treating apple slices with either FA or SAS before dehydration than all other antimicrobial treatments. Decreasing apple surface pH was statistically correlated with decreasing survival of Salmonella following dehydration. These results may provide methodology applicable to the food industry for increasing the inactivation of Salmonella during the dehydration of apple slices.